The present invention broadly relates to filament winding and, more specifically, pertains to a new and improved system for catching and winding a thread to form a thread package on a bobbin tube.
The invention particularly relates to an improved thread winding machine including a piston and cylinder unit, to a method and apparatus for performing automatic changeover of winding of a thread, and to an apparatus for forming an overwound transfer tail or thread reserve.
The term "thread" refers particularly, but not exclusively, to threads of synthetic plastic filament in mono-filamentary or multi-filamentary form. For reasons which will be apparent from the following description, the invention is designed particularly, but not exclusively, for use in winding machines for winding packages of relatively high denier (titer) thread, and especially for automatic, so-called wasteless, winders for this purpose.
Generally speaking, the automatic changeover apparatus and method of the present invention serve for the automatic changeover of winding of a thread from a completed package on an outgoing chuck to an empty bobbin on an incoming chuck.
The piston and cylinder unit of the thread winding machine of the present invention is of the type comprising a cylinder housing with first and second chambers, dividing or separating means between the first and second chambers, and a piston movable longitudinally in the first chamber.
The apparatus for forming an overwound thread transfer tail of the present invention is of the type comprising a thread guide and a movable member movable in a predetermined direction and connected to the thread guide.
The method of the present invention is for forming an overwound thread transfer tail.
Automatic winders for synthetic filament threads are now very well known in the relevant art, and will not be described herein in detail. One example of a so-called "revolver" machine of this type is described and illustrated in U.S. Pat. No. 4,298,171, granted Aug. 15, 1978, although many alternative designs for this kind of machine are also known.
An automatic winding machine operating on a different principle (different "machine geometry") is illustrated and described in the European Patent Application published under the Publication No. 73,930 and corresponding with U.S. Pat. No. 4,454,952, granted June 19, 1984, No. 4,497,450, granted Feb. 5, 1985, and No. 4,524,918, granted June 25, 1985. Still further machine designs have been proposed from time to time for automatic winding machines.
Common to all such designs is a plurality of chucks or spindles individually rotatable about their respective longitudinal chuck axes. Each chuck is adapted to receive one or more bobbin tubes and has means for securing received bobbin tubes to the chuck structure for rotation therewith about the chuck axis.
Thread is delivered to the winder or winding machine continuously. When a delivered thread has been wound into a completed package on one chuck, it is transferred to another chuck on which winding of a new package starts, the thread being severed between the two chucks.
Automatic winders are commonly used to wind threads of relatively heavy denier (titer), for example threads for industrial purposes (technical titer), tire cord, carpet yarn et cetera. With such strong yarns it is necessary to cut the thread between the two packages during a changeover. It is not sufficient to rely upon tearing of the thread between the two packages as in the case of relatively weak textile threads. It is therefore normal practice to provide thread catching and cutting devices incorporated in the structure of each chuck, e.g. as shown in U.S. Pat. No. 4,106,711, granted Aug. 15, 1978, or as described (but not illustrated) in U.S. Pat. No. 4,477,034, granted Oct. 16, 1984.
Where a thread-catching and cutting device is incorporated in the chuck structure, then it is normally recessed slightly below the outermost cylindrical surface of that chuck structure. This enables a bobbin tube or tubes to be passed over the thread catching and cutting device as they are moved onto and off the chuck by axial movement relative to the chuck. A problem then arises in that the thread must first of all be engaged with the recessed catching and cutting device and then must "climb" out of that device onto the neighboring bobbin tube in order to start formation of the desired package thereon.
Systems have already been proposed for operation during the changeover from a completed package to a new chuck, firstly to engage the thread with a guide surface on the new chuck and then to move the thread axially of the chuck into the catching and cutting device and then onto the adjacent bobbin tube. Such a system is shown, for example, in U.S. Pat. No. 3,920,193, granted Nov. 18, 1975. Although not referred to in that patent, it is also common practice to provide the axial end face of each bobbin tube with a notch which catches the thread as the latter is moved axially past the bobbin end face and which assists the thread to climb onto the bobbin tube.
Despite these precautions, it is still often found that the thread has difficulty climbing onto the tube, so that several thread windings are formed on the chuck structure itself beside the axial face of the tube before the thread finally succeeds in passing onto the bobbin outer surface. This is very disadvantageous for several reasons.
When the subsequent winding operation is completed, with a full package on the bobbin tube, the continuously delivered thread is transferred to another chuck and the chuck with the completed package is braked to a standstill. The thread catching device is usually arranged to release the thread end at this stage (e.g. as described in U.S. Pat. No. 4,106,711 referred to above), so that the completed package can be withdrawn from the chuck by passing back over the recessed catching device. In so doing, it also passes over the additional windings which have been formed on the chuck because of the failure of the thread to pass cleanly onto the bobbin tube at the start of the winding operation. These windings are now relatively loose, and they are drawn out into a long tail extending back between the bobbin tube and the chuck surface.
With heavy packages, and with some bad luck in maneuvering the package relative to the chuck, the thread tail can actually jam the bobbin tube relative to the chuck, causing considerable difficulty in removal of the package. Even where the package does not jam completely on the chuck, the drag exerted on the thread tends to loosen the transfer tail windings formed, for example as described in the previously mentioned U.S. Pat. No. 3,920,193, between the end of the bobbin tube and the actual package structure thereon. The lack of a secure and cleanly formed transfer tail winding can severely adversely affect the value of the whole package, even though the bulk of the thread material is contained in the package structure itself.
Furthermore, it may be necessary to clear the incorrectly formed windings from the chuck structure before the next winding operation can start, if such windings are not drawn off the chuck with the associated package. However, it is now common practice to provide relatively long chucks and to form a plurality of packages simultaneously on a single chuck from a corresponding plurality of continuously delivered threads. The chucks commonly extend cantilever-fashion from a headstock containing drive and support systems for the chucks. The machines are usually arranged at a very close spacing so that very little access-room is available around the chucks themselves. If, now, the incorrect windings are formed on the portion of the chuck structure adjacent the inboard bobbin tube, then severe difficulty is experienced in clearing such windings so as to prepare for the next winding operation.
Despite all precautions taken with systems previously available, it has been common to produce defective reserve windings or transfer tails due to the faults referred to above, and this represents a substantial economic loss due to the diminution in value of the complete packages associated therewith.